Date of birth
Theo began his career at Stoke City, as he progressed through the Potters' youth ranks before signing for Oldham Athletic in 2015.
After a brief loan spell at Chorley, Theo signed for Walsall a year later and it was at this point that he started to build up his first team experience, as he completed two successful loan spells at Chester.
In July 2017, Theo signed for Neil Aspin's Gateshead and went on to make thirty-four appearances for The Heed - scoring on two occasions.
Aspin clearly rated the tenacious and committed defender very highly, as shortly after his move to Port Vale, Theo would also make the move back to the Potteries.
Vassell would make fifteen appearances for The Valiants last term and these elicited much praise from fans and team-mates alike.
Theo signed for Macclesfield Town during the summer of 2019 on a one-year deal.